Method for treating overburden rock grouting filling and running channel

Abstract

The application discloses a method for treating a slurry running channel of overburden rock grouting and filling, and is suitable for the field of coal mine filling mining. After the position of slurry running is determined, the horizontal distance between the slurry running outlet of overburden rock and the grouting borehole is calculated, the specific parameters and filling amount of the swelling plugging material are determined for filling, the plugging material is filled into the slurry running channel by using the pressure difference, the swelling plugging material expands in the slurry running channel, the original opening of the slurry running channel is plugged as small fissures, and then the quick-setting slurry with good fluidity is used to fill the small fissures, so that the purpose of completely plugging the slurry running channel is achieved. The method has good plugging effect, can permanently plug the slurry running channel, is not prone to secondary slurry running, does not affect normal grouting and subsidence control effect, has low cost, short time consumption, high reliability, high plugging accuracy, simple method and high repeatability.

Description

Technical Field

[0001] This invention belongs to the field of coal mine backfilling mining and relates to a method for treating grout leakage channels in overburden grouting backfilling. It is applicable to treating grout leakage problems caused by geological structures (such as faults) and geological boreholes in the backfilling working face of coal mine overburden grouting backfilling mining. Background Technology

[0002] Overburden grouting and filling technology, as an important branch of green mining, has been widely applied in coal mining enterprises and has achieved good results, effectively solving the problem of coal mining pressure. The principle of this technology is to fill the overburden fissures below the selected key layer with high-pressure grouting. Under the action of grouting pressure, the fractured rock mass below the isolation layer is continuously compacted to form a compacted support zone, ensuring the stability of the overburden structure, preventing deformation and fracture of the key overburden layer, and controlling surface subsidence.

[0003] In the application of overburden isolation grouting and filling technology, the influence of geological structures (such as faults) poses a possibility of grout leakage along the fault, affecting the grouting and filling work. Existing solutions involve immediately stopping grouting and filling upon detection of leakage, resuming grouting at a low pump rate after a period of inactivity, and adding a coagulant (such as cement) to the filling grout. However, this method has the following drawbacks: ① The addition of the coagulant can easily clog the grouting boreholes during the filling process; ② The treatment process is slow, and the suspension of grouting and mining at the working face can easily cause surface subsidence; ③ If the leakage channel is a fault with a large opening, the shape and size of the leakage channel make it difficult to completely block the leakage channel through grout deposition; ④ High requirements are placed on grouting pressure control, and large fluctuations in filling pressure can easily cause the leakage channel to reopen and expand. Summary of the Invention

[0004] To address the shortcomings of the aforementioned technologies, this invention provides a method for treating grout leakage channels in overburden grouting, which is low-cost, time-efficient, highly reliable, accurate, and simple to control, ensuring uninterrupted grouting at the filling face. This method involves adding an expanding plugging material during the grouting process to block the leakage channels, transforming the original large channels into small fissures. After the expanding material plugging is completed, a quick-setting grout with good fluidity is filled into the grouting boreholes to completely seal the small fissures, achieving a permanent sealing effect on the grout leakage channels during uninterrupted grouting and preventing the filling grout from overflowing.

[0005] To achieve the above-mentioned technical objectives, the method for treating grout leakage channels in overburden grouting of the present invention includes the following steps:

[0006] a. Determine the location of the grout outlet. Based on the type of grout channel and geological parameters, determine the location of the grout outlet at the separation layer; calculate the distance L (m) from the grout outlet at the separation layer to the bottom of the grouting borehole.

[0007] b. Measure the flow rate Q (m³) of the filling grout at the grout outlet using a grout flow meter. 3 The opening of the slurry channel is calculated using the flow rate v (m / h) and the flow velocity v (m / h).

[0008] c. Based on the opening of the slurry channel, select the appropriate particle size of the expansion plugging material under the opening condition, and determine the delayed expansion time of the expansion plugging material. The delayed expansion time must ensure that the expansion plugging material only begins to expand after entering the slurry channel.

[0009] d. Determine the filling ratio in the slurry runoff channel and calculate the filling volume of the expansion plugging material;

[0010] e. After discovering the grout leakage outlet, reduce the grout concentration and filling flow rate without stopping the grouting process; add an expansion plugging material to the grout, and use grouting to seal the large channel into a small crack.

[0011] f. Use quick-setting grout with good fluidity to seal the small cracks in the grout flow channel for a secondary purpose, so as to completely seal the small cracks.

[0012] In step a, the types of grouting channels are divided into geological boreholes and faults. The grouting outlet of a geological borehole is located at the borehole opening. For grouting in a fault, the location of the grouting outlet is calculated based on the vertical distance H between the grouting outlet and the filling layer and the fault dip angle λ. The calculation method is to add or subtract H / tanλ from the distance from the grouting borehole to the grouting outlet.

[0013] In step b, the slurry discharge channel in the geological borehole is an approximately uniform tubular shape. For fault slurry discharge, the slurry discharge channel is considered equivalent to a tubular shape with a uniform opening at all locations; therefore, the diameter of the slurry discharge channel is...

[0014] In step c, the expansion sealing material is a paraffin-coated superabsorbent resin with two characteristics: first, the material is an expansion material, and its volume after expansion is 100 times its original volume; second, the material has a delayed expansion effect, that is, it does not expand in volume within the set delayed expansion time, but rapidly expands to its maximum volume after the set delay time is reached, and the expansion time is adjustable.

[0015] In step c, the particle size of the expansion sealing material is at most 1 / 10 of the size of the slurry channel, that is... The flow velocity of the filling grout in the flow channel within the delamination layer is known to satisfy... Where k is the velocity attenuation coefficient after entering the delamination layer from the grouting borehole, and q s Grouting flow rate (m³) for grouting boreholes 3 / h), A is the cross-sectional area of ​​the grouting borehole (m²). 2The time it takes for the expansion plugging material to diffuse along the flow channel to the grout outlet after being filled into the grouting borehole is L / v′(h), i.e. At this point, the particle size of the expansion plugging material can be determined to be... The delayed expansion time of the expansion plugging material is

[0016] In step d, the length of the slurry channel is The cross-sectional area of ​​the slurry channel is If the expansion ratio of the expansion sealing material is 100 times its own volume, then based on a 50% filling rate in the slurry leakage channel, the required volume of expansion sealing material is: The required mass of expansion sealing material is In step e, the added mass is... Expansion sealing material.

[0017] In step f, a small amount of expanded plugging material was found at the grout outlet, indicating that the initial sealing effect of the grout outlet channel was good. After the grouting and filling were officially resumed, the grout outlet channel no longer experienced grout leakage, indicating that the grout outlet channel sealing was completed.

[0018] In step f, the quick-setting grout is quick-setting cement.

[0019] Beneficial Effects: This invention analyzes specific filling conditions and grout leakage types, designing a process of volume expansion sealing with expanding plugging material and secondary grouting sealing to completely seal grout leakage channels. This invention does not affect the normal implementation of grouting and filling, ensuring its uninterrupted operation and guaranteeing the effectiveness of surface subsidence control. It overcomes the shortcomings of traditional grout leakage control methods, which require stopping mining and grouting, leading to increased surface subsidence. Furthermore, the sealing method requires no additional procedures, utilizing only existing grouting boreholes for filling. It is applicable to sealing various types and openings of grout leakage channels, with a simple implementation process, requiring less sealing material, low cost, and good control effect, fundamentally improving the surface subsidence control effect of grouting and filling projects. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the principle of the overburden grouting filling method for treating grout leakage channels of the present invention;

[0021] Figure 2 This is a schematic diagram showing the horizontal distance between the grout outlet and the grouting borehole of the present invention;

[0022] In the diagram: 1 - Grouting station; 2 - Grouting borehole; 3 - Key overburden layer; 4 - Expansion plugging material; 5 - Grout outlet; 6 - Separation grout outlet; 7 - Isolation layer; 8 - Working face; 9 - Filling layer; 10 - Overburden; 11 - Grout channel; 12 - Grout flow direction; 13 - Horizontal distance between grouting borehole and grout outlet; 14 - Working face advancement direction; 15 - Grout flow meter; 16 - Filling layer depth; 17 - Fault dip angle. Detailed Implementation

[0023] The invention will now be further described with reference to the accompanying drawings, as follows: Figure 1 and Figure 2 As shown, overburden grouting and backfilling technology is used for backfilling mining of working face 8. A grouting station 1 is established on the ground, and grouting boreholes 2 are drilled to the designed backfilling layer 9. The backfilling layer 9 is located below the key overburden layer 3 and is separated from the water-conducting fracture zone by an isolation layer 7. During the mining of working face 8, fly ash slurry is injected into the backfilling layer 9 through the grouting boreholes 2 to form a grouting separation layer. During grouting and backfilling mining, grout leakage was found on the ground, i.e., there is a grout leakage channel connecting the separation layer to the ground, and a grout leakage outlet 5 appears on the ground. Based on geological data, the grout leakage channel 11 is determined to be a fault. In response, this invention provides a method for treating grout leakage channels in overburden grouting and backfilling, including the following steps:

[0024] a. Determine the location of the grout outlet 5, and determine that the type of the grout channel 11 is a fault. Calculate the horizontal distance L (m) from the grout outlet 6 to the bottom of the grouting borehole 2 based on the burial depth 16 of the filling layer (i.e., the grouting separation layer) and the fault dip angle 17 (λ). If the grouting borehole is a vertical borehole, the calculation method is to determine the horizontal distance 13 between the grouting borehole and the grout outlet, and then add or subtract H / tanλ (m) from the horizontal distance 13 between the grouting borehole and the grout outlet.

[0025] b. At the grout outlet 5, the flow rate Q (m³) of the grout flowing out was measured using a grout flow meter 15. 3 Given the flow rate v (m / h) and velocity v (m / h), and considering the slurry channel 11 as an equivalent tubular structure with a uniform opening at all locations, the equivalent diameter of the slurry channel 11 is:

[0026] c. To meet the injectability requirements, the particle size of the expandable sealing material 4 is selected to be at most 1 / 10 of the equivalent diameter of the slurry channel 11 (here, the particle size of the expandable sealing material refers to the particle size of the expandable sealing material before expansion). Assume the flow velocity of the filling grout within the filling layer (separation layer) satisfies Where k is the velocity attenuation coefficient after entering the delamination space from the grouting borehole, and q s (m 3 / h) is the grouting flow rate of grouting borehole 2, and A is the cross-sectional area of ​​grouting borehole 2 (m²). 2 The time it takes for the expansion plugging material 4 to diffuse from the grouting borehole 2 into the delamination outlet 6 is L / v′(h), i.e. At this point, the particle size of the expansion plugging material can be determined to be 4. The delayed expansion time of the expansion plugging material 4 was determined to be...

[0027] The expansion sealing material uses a paraffin-coated superabsorbent resin. Its working mechanism is as follows: the paraffin coating prevents the resin from combining with water, thus preventing the material from expanding; after immersion in water for a period of time, due to the slow penetration of water molecules, the resin combines with water and expands, causing the paraffin to burst. Afterward, the resin mixes more thoroughly with the water, resulting in full expansion. The delayed expansion time of the expansion sealing material can be adjusted depending on the amount of paraffin used.

[0028] d. Calculate the filling volume of expansion sealing material 4; the length of the slurry leakage channel 11 is... The cross-sectional area of ​​the run-through channel 11 is If the expansion ratio of the expansion sealing material 4 is selected to be 100 times its own volume, then based on a 50% filling rate in the slurry channel 11, the required volume of the expansion sealing material 4 is: The required mass of expansion sealing material 4 is

[0029] e. Upon discovering grout leakage, reduce the grout concentration and flow rate without interrupting the original grouting process; add particles with a diameter of [missing information] to the grout. Delayed inflation time is 4. Expansion sealing material, with a mass of [missing information]. Grouting and filling achieve the purpose of sealing large channels into small cracks;

[0030] f. A small amount of expanded plugging material 4 was found at the grout outlet 5. At this point, it was considered that the initial sealing effect of the grout channel 11 was good. Then, the small cracks at the grout channel 11 were sealed a second time by filling the grouting borehole 2 with a quick-setting grout with good fluidity (e.g., modified quick-setting cement) to achieve the purpose of completely sealing the small cracks. At the same time, the pressure bearing capacity of the grout channel 11 was ensured. After the grouting was officially restored, the grout outlet 5 no longer experienced grout leakage. It was considered that the sealing of the grout channel was completed.

Claims

1. A method for treating grout leakage channels in overburden grouting, characterized in that, Includes the following steps: a. Determine the location of the grout outlet. Calculate the location of the grout outlet from the fault based on the vertical distance H between the grout outlet and the filling layer and the fault dip angle λ. Calculate the distance L from the grout outlet to the bottom of the grouting borehole. The calculation method is to add or subtract H / tanλ from the distance from the grouting borehole to the grout outlet. b. At the grout outlet, use a grout flow meter to measure the flow rate Q and velocity v of the grout flowing out, and calculate the opening of the grout outlet channel accordingly; if the grout outlet channel is equivalent to a tube with a uniform opening at all locations, then the diameter of the grout outlet channel is... ; c. Based on the opening of the slurry channel, select the appropriate particle size for the expansion plugging material under that opening condition, and determine the delayed expansion time of the expansion plugging material. This delayed expansion time must ensure that the expansion plugging material only begins to expand after entering the slurry channel; the particle size of the expansion plugging material is 1 / 10 of the size of the slurry channel, i.e. The flow velocity of the filling grout in the flow channel within the delamination layer satisfies Where k is the velocity attenuation coefficient after entering the delamination layer from the grouting borehole, and q s Let A be the grouting flow rate of the grouting borehole, and A be the cross-sectional area of ​​the grouting borehole. The time it takes for the expanding plugging material to diffuse along the flow channel to the grout outlet after filling the grouting borehole into the delamination layer is calculated as follows: ,Right now The delayed expansion time of the expansion plugging material is: ; d. Determine the filling ratio in the grout leakage channel and calculate the filling volume of the expansion sealing material; the length of the grout leakage channel is... The cross-sectional area of ​​the slurry channel is If the expansion ratio of the expansion sealing material is 100 times its own volume, then based on a 50% filling rate in the slurry leakage channel, the required volume of expansion sealing material is: The required mass of expansion sealing material is ; e. Upon discovering a grout leakage outlet, reduce the concentration and flow rate of the filling grout without suspending grouting; add an expanding plugging material to the filling grout, and use grouting to seal large channels into small cracks; the filling grout is fly ash grout. f. Use quick-setting grout with good fluidity to seal the small cracks in the grout flow channel for a secondary purpose, so as to completely seal the small cracks.

2. The method for treating grout leakage channels by grouting and filling overburden as described in claim 1, characterized in that: In step c, the expansion sealing material is a paraffin-coated superabsorbent resin.

3. The method for treating grout leakage channels in overburden grouting according to claim 2, characterized in that: In step f, a small amount of expanded plugging material was found at the grout outlet, indicating that the initial sealing effect of the grout outlet channel was good; after the formal resumption of grouting and filling, the grout outlet no longer experienced grout leakage, indicating that the grout outlet channel sealing was completed.

4. The method for treating grout leakage channels in overburden grouting according to claim 1 or 3, characterized in that: In step f, the quick-setting grout is quick-setting cement.

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